Cast iron is a popular material used in various industries for its durability and strength. But, just like any other material, it is prone to rusting and damage over time and requires repair. The good news is welding is not only the last resort to repair it.
There are a variety of ways to fix cast iron that are simple, straightforward, and don’t require a welding torch. Whether you’re a DIY enthusiast or a professional repairman, you’ll find the information in this blog informative and helpful. Let’s dig deeper to learn how to fix cast iron without welding.
3 Methods to Fix a Cast Iron without Welding
The three commonly used methods to repair cast iron without welding it are:
- Cold Bonding
- Epoxy Putty
Read the blog to the bottom to learn about these procedures in detail.
1: Repairing Cracked Cast Iron Using Brazing
Brazing is a metal joining process in which two or more metal parts are joined together by heating them to a temperature above their melting point and then introducing a filler metal (brazing alloy) into the joint to form a bond between the parts. The filler metal has a lower melting point than the base metals being joined and is therefore melted and flowed into the joint, where it cools and solidifies to form a strong bond.
1: Select a filler rod depending on the application of the cast iron part. Filler bars made of nickel or brass are most commonly used in cast iron brazing. Make sure to select the metal that offers great strength.
2: Once you have chosen the filler bar, clean the crack surface to remove any layers of impurities and oxides using a grinder to create a cross-section in the crack where the filler bar would sit. This will help the melted filler bar to flow fully into the crack.
3: Use a stainless steel brush to clean the ground area of the cast iron piece to remove any residue left after grinding.
4: Apply heat to the cast iron piece using a technique such as an oven, gas grill, or weed burner to heat the cast iron part slowly. I won’t recommend using a brazing torch as it causes more cracking and warping on the cooler parts of cast iron because of the heat intensity.
5: It’s time to insert the melted filler metal into the crack. But before doing so, maintain the optimum temperature around the crack before filling the metal. For that purpose, you can use external heating sources to concentrate heat around the crack.
6: Once you are done with the repairing process, let it cool slowly by placing the repaired piece in a container full of sand for at least a day or two. Remember, after the brazing procedure, don’t let the cast iron piece sit in the air to cool down, as it may crack.
2: Repairing Cracked Cast Iron Using Epoxy Putty
Epoxy putty is a glue-like but a bit hard material. It is used to fix cast-iron cracks but is temporarily fixed until a permanent solution is taken up. At room temperature, this epoxy putty adhesive substance is used for space-filling.
- First, you will need to buy epoxy putties. You will easily find them in any local hardware store. We prefer to use JB weld or quick steel. These come in two tubes and serve as glue to fill the crack.
- Clean the cast iron surface with 80-grit sandpaper to remove any impurities from the surface. This process will also make the surface rough to bond the glue with the surface strongly. Remember to use back-and-forth movements for cleaning surfaces instead of circular movements to prevent the crack from widening.
- Clean the surface area with soap, water, and a rag to remove any particular sandpapering. Before moving further, let the cast iron area dry completely.
- Squeeze the putty out of the tube on some surface, such as cardboard, and mix it using a knife. See the manufacturer’s instructions on how to mix it printed on the packing.
- Apply the putty to the cracked surface with the knife. Make sure to fill the crack with putty. Scrap off any excess putty before it gets hard to remove it easily. We recommend you not handle the cast iron piece before 24-hours after putty application.
- Ensure to paint over the sealed crack piece where you filled the putty to match it with the rest of the cast iron piece and enhance durability.
3: Repairing Cracked Cast Iron Using Cold Metal Stitching
A method that we can use to repair cracked metal that can’t be repaired using traditional procedures, like welding. This process involves lacing up the crack metal using any other metal. You can use this method to repair aluminum, cast steel, and cast iron.
Cold metal stitching’s popularity is increasing with every passing day because of its ability to repair any structures that are not easy to disassemble or replace. Construction workers around the world use this technique to preserve old buildings.
Shipping companies worldwide use this method to repair old booked engines rather than replace the old ones with new ones. The method is well-known in mining, transportation, construction, heavy-engines machinery, construction, and many other areas.
Let’s follow a step-by-step procedure for using cold metal stitching to repair cast iron.
1. Metal Crack Diagnosis: First, you need to look at the crack you will repair. This method lets you ideally repair the cracks with a thickness of 3/16 inches up to a foot. You can ignore the length of the crack, as it does not matter. The nature of the crack decides whether it can be repaired or another cast iron piece needs to be created.
2. Drilling Holes Along the Crack: Now, place the holes on the crack at a specified distance. We recommend using a guide to place holes along the crack accurately. It’s unnecessary to have the same number of hole sets. There could have been more holes on one side and a few on another. The goal is to create stitching points strong enough to bond the cracked iron.
3. Connecting Hole Rows: Once the holes are drilled, you need to connect them. This will make it easier to insert the metal stitches, strengthening the cracked cast iron. You must connect the holes using a large chisel without creating space in the metal.
Once you insert the metal key, the rounded shoulders achieved through drilling will act as the holding points. Maintaining the outer diameter of the drilled holes while connecting them is very important.
4. Insertion of Metal Keys or Stitching: Metal keys are the most vital element of the procedure. Because they provide the strength required to keep the repaired metal together, make sure to use the metal that offers extended strength, or you will have to repeat the process.
The length of the metals must be the same as of the holes you drilled in the first place. This will add strength to the whole surface area and prevent further cracking. Make sure to keep them tight to create a solid bond; there should be a little gap between the original piece and the metal stitch. You will require a mallet to press fit the stitch in.
You should worry about the extra material from the original part surface. It can be easily dealt with in the finishing process.
5. Sewing the Metal Stitches: Joining the cracked cast iron piece only with metal stitched is not enough. Because these metal stitches may break upon putting heat and intensity on the cast iron piece. So, you need to nail in the screws between the metal stitches.
Neighbouring screws and metal stitching keys should be close to each other. Tightening the stitches will create a robust bond between the repaired metal and the cracked cast iron.
Just as with the metal keys, it’s okay if there is an extra metal that may be sticking up from the screws that have been installed. The excess material will come in handy when finishing the surface and appear as one whole cast iron piece.
Lining up the flush with the original cast iron piece’s surface will help eliminate weak spots and the reoccurring crack chances.
6. The Finishing Steps: The final step involves chiselling away the extra material from the metal stitches and the stitching screws. You need to remove the metal material as much as using the chisel. The rest will be done using the grinding tool. The finishing process is vital in restoring the cast iron to its initial position. Use the excess metal to hide the repair work for a cleaner outlook.
How to Prepare Cast Iron Piece Before You Start Repairing It
If you are looking to buy a new cast iron piece, it could cost you extra bucks, so repairing it is a good option. You are supposed to clean the cast iron piece to remove any residue, regardless of which method you opt.
Following the guidelines below will help you efficiently clean cast iron pieces before repairing them.
Cracking is not the only problem with cast iron items; they might also get rusty or burnt. First, you must sprinkle salt on its surface if it’s burnt. Afterwards, use a steel brush or scrub to clean the surface. Using a damp brush could clean it more efficiently. However, if the burn is difficult to eliminate, the plastic scraper can come in handy.
On the other hand, if the cast iron piece has rust, using a scrub or detergent can help to get rid of it. Eliminating rust timely could prevent cast iron from further damage.
You can restore the colour of your cracked cast iron piece by scrubbing it with steel wool. First, you need to scrub it to remove dirt traces from it. Then wash it with soap and warm and let it dry to restore its colour.
Once the piece is dry and clean, you need to eliminate defects like porosity with a grinder that will make the surface ready to repair.
Seasoning of a Cracked Cast Iron
If your cast-iron pieces, like pans, etc., are rusting, you may try seasoning. It includes the following procedure:
Take water and vinegar in equal portions and dip the cast iron in for 30 minutes. Now take it out from the solution and apply unrefined oil to it. Start seasoning by wiping it with toilet paper, and oven it for 5 minutes at 200 degrees centigrade. Repeat this process 5 to 6 times to get better results. This process can help restore the cast iron to its original shape, free of rust and cracks.
Ultimately, it can be understood that cracked cast iron can be fixed without welding. However, It is difficult and risky as the temperature may exceed the safe limit, which may cause burning. So, you should move to the safer ideas rather than opting for welding to fix your cast iron-made things such as water pumps, pans, drums, etc. These ideas aim only to produce pieces of showroom quality that could be pleased having been in the gallery, home, or office.
Read the Articles Listed Below to Learning How to Joint Metals Without Welding
- How to Join Steel Pipes without Welding?
- How to Join Metals without Welding?
- How to Weld Cast Iron to Steel